(1) Field of the Invention
The present invention relates in general to a multiple roller spinning machine for spinning vehicle wheels, and in particular to various improvements in such a machine. The improvement include means for sliding the roller holder horizontally in a direction parallel with the axis of spinning to thereby enable the roller to draw a range wider than its size across the U-cross section portion of the wheel material outside periphery, means for replacing the roller holder, means for replacing the multiple rollers, and means for feeding work, centering it between the rotating spindles, and discharging it at the end of the spinning in an automatic manner.
(2) Description of the Prior Art
Wheels for buses, trucks and general passenger cars may be produced by spinning from workpiece or wheel materials shaped like a drum flanged on either side, of largely U- or V-cross section along its outside priphery, so formed at the previous process stage. In typical spinning, the wheel material, while being spun about its own axis between the headstock main spindle and tailstock driven spindle, is subjected at its U-cross section outside periphery to drawing by a roller.
The headstock main spindle and the tailstock driven spindle are held in axial alignment with each other and rotated at a very high speed about their axis by an external drive. They each carry at their forward end a die formed at its surface with a particular profile or contour. In fact, between the dies of both spindles is clamped the wheel material, with both of its largely concaved circular sides tightly pressed against the profiled die faces, and set into high speed rotation. Roller drawing at the outside priphery of the wheel material during revolution enables it to assume the profile of the dies underneath at that outside periphery. As a result of spinning, the wheel material may be transformed to the cross section depicted in FIG. 3(4) from its original shape as shown in FIG. 3(1).
A typical conventional spinning machine has a single forming roller, normally elliptical in cross section. However, it is generally difficult or often impossible for a single roller to draw the wheel material from its initial simple shape, as shown in FIG. 3(1), to a desired final profile as a vehicle wheel. In some instances, therefore, a set of rollers different in shape and size, each designed for a different sequential step of drawing, from rough to finishing drawing, are employed, and are assembled into the roller holder one after another according to the progress of the drawing operation.
In other instances, the holder shifts its roller in a direction perpendicular with the axis of spinning to thereby enable it to draw at different points across the U-cross section rim of the wheel material. In this manner, the one and the same roller can draw a ranger wider than its size. In either example, operation demands considerable time and repeated cycles of jobs, changing or shifting the roller over and over again, with resultant low productivity, and have not been acceptable, particularly in mass-scale production.
Japanese utility model No. 57-152227 has been proposed to solve some of these problems. It discloses a multiple roller spinning machine having a set of different rollers assembled in the holder to perform different steps of the operation in an automatic continued manner. In one embodiment of the invention taught in this utility model application, the multiple rollers 34 are arranged in a linear row in the holder 22, as shown in FIG. 4. The holder 22 is coupled at one end thereof to a hydraulic cylinder 41 which moves through its axially movable piston rod the holder in a direction parallel with the axis of spinning to thereby bring the multiple rollers sequentially into a position just above the wheel material clamped between the dies of the driving and driven spindles. Also, the holder 22 is coupled at its top to another hydraulic cylinder 40 which moves its axially movably piston cylinder through the holder 22 vertically. In operation, the hydraulic cylinder 40 is actuated to bring the roller now just above the wheel material into pressure contact against its rim for drawing, the material being spun at high speed between the dies. When the drawing is completed by this roller, the hydraulic cylinder 41 is actuated to bring the next roller in for the subsequent step of drawing. In this way, the work can be subjected to drawing by multiple rollers, desirably from rough to finishing drawing.
In another embodiment, as shown in FIG. 5, the rollers 34 are arranged radially about a common center at 6 in the holder 22, and rotatably disposed for free rotation about the center 6. Rotation of the holder brings the rollers sequentially into a position just above the wheel material 12 clamped between the dies of the driving and driven spindles. The holder 22 is coupled at its top to a hydraulic cylinder 40 which moves its piston rod through the holder to thereby bring the roller now just above the material into pressure contact with the material rim. In this way, the workpiece can be subjected to drawing by multiple rollers.
Japanese utility model application No. 57-15227, while found advantageous in efficiency and, to some degree, productivity, over those single-roller spinning machines, shares many of these problems with most prior art spinning machines.
A most serious problem with the prior art is that the rollers are incapable of shifting in a direction perpendicular with the axis of spinning.
Secondly, considerable inefficiency results from the manual procedure of feeding the wheel material to be spun, centering it between the headstock and tailstock spindles, and, at the end of the spinning process, removing it from the machine to provide room for the next material in the queue. Time and manpower involved in this manual procedure is considerable, particularly so in mass-scale production. Further, centering the material in position demands extreme effort on the part of the operator.
Thirdly, replacing the roller also consumes much labor and time. When a forming roller has to be changed in the conventional spinning machines, it is normally removed, together with its bearing, from the machine, and suspended in air with a crane or similar special hoisting device. With the roller hung in this way, tightening bolts are loosened to release the old roller, and the new roller is fitted and secured in position with the bolts. This job does not only demand an extremely long time of concentrated labor, but it also tends to expose the operator to a hazadous condition due to the danger of possible injury by impact from a swinging or accidentally falling roller bearing. Further, loosening the bolts and holding the new roller in a fixed position as it is secured in the bearing are very difficult and cumbersome, since the suspended bearing easily allows swinging motion from even the slightest external force exerted on it during the work. Because of these problems in the main, those prior art spinning machines have not been widely acceptable.